mference is 21,125 kilometers (13,000
miles). His surface is only 29/100 of the terrestrial surface, and his
volume only 15/100 of our own.

This difference in volume causes Mars to be an earth in miniature. When
we study his aspects, his geography, his meteorology, we seem to see in
space a reduction of our own abode, with certain dissimilarities that
excite our curiosity, and make him even more interesting to us.

The Martian world weighs nine times and a half less than our own. If we
represent the weight of the Earth by 1,000, that of Mars would be
represented by 105. His density is much less than our own; it is only
7/10 that of the Earth. A man weighing 70 kilograms, transported to the
adjacent globe, would weigh only 26 kilograms.

The earliest telescopic observations revealed the existence of more or
less accentuated markings upon the surface of Mars. The progress of
optics, admitting of greater magnifications, exhibited the form of these
patches more clearly, while the study of their motions enabled the
astronomers to determine with remarkable precision the diurnal rotation
of this planet. It occurs in 24 hours, 37 minutes, 23.65 seconds. Day
and night are accordingly a little longer on Mars than on the Earth, but
the difference is obviously inconsiderable. The year of Mars consists of
668 Martian days. The inclination of the axis of rotation of this globe
upon the plane of its orbit is much the same as our own. In
consequence, its seasons are analogous to ours in intensity, while twice
the length, the Martian year being almost equal to two of our years. The
intensity of the seasons is indeed more accentuated than upon the Earth,
since the orbit of Mars is very elongated. But there, as here, are three
quite distinct zones: the torrid, the temperate, and the glacial.

By means of the telescope we can follow the variations of the Martian
seasons, especially in what concerns the polar snows, which regularly
aggregate during the winter, and melt no less regularly during the heat
of the summer. These snows are very easily observed, and stand out
clearly with dazzling whiteness. The reader can judge of them by the
accompanying figure, which sums up the author's observations during one
of the recent oppositions of Mars (1900-1901). The size of the polar cap
diminished from 4,680 kilometers to 840. The solstice of the Martian
summer was on April 11th. The snows were still melting on July 6th.
Sometimes they disappear